Controllers for heat supply units

ABSTRACT

The present invention relates to an electronic controller for a boiler. The controller includes a control circuit that is adapted to provide a sequence of control signals to periodically turn the boiler ON and OFF during successive operational periods of the controller. Each operational period is started by an activation signal provided to the controller form an external device (e.g. a timer or thermostat and is ended by deactivation signal. At least one period of time for which the boiler is turned ON is longer than at least one other period of time for which the boiler is turned ON during a particular operational period.

TECHNICAL FIELD

The present invention relates to controllers for heat supply units (e.g. gas or oil-fired boilers) that form part of a heating system.

SUMMARY OF THE INVENTION

The present invention provides a controller for a heat supply unit (e.g. a boiler) for supplying heat to a heating system, the controller including a control circuit that is adapted to provide a sequence of control signals to periodically turn the heat supply unit ON and OFF during successive operational periods of the controller, each operational period being started by an activation signal provided to the controller from an external device and being ended by a deactivation signal provided to the controller from an external device, wherein at least one period of time for which the heat supply unit is turned ON is longer than at least one other period of time for which the heat supply unit is turned ON during a particular operational period.

The controller may be connected to an existing central heating (or primary) controller or integrated with the main boiler controller, for example. The control circuit implements a software control program that provides savings in fuel consumption and reduces CO₂ emissions. There are three heating phases in a typical heating cycle. Phase 1 is when the heat supply unit (e.g. boiler) runs ‘full bore’ to heat the water in the heating system to its desired (or ‘target’) temperature. Phase 2 is after the target temperature of the water has been reached, but the heat supply unit remains activated until a desired (or ‘target’) building/room temperature is reached and the heat supply unit is deactivated by a thermostat. Phase 3 is after the thermostat has been engaged and periodically activates and deactivates the heat supply unit to maintain the building/room at its target temperature. The control program particularly saves fuel during phase 1 and phase 2 of the heating cycle.

In a typical arrangement the sequence of control signals will turn the heat supply unit ON for a longer period of time at the start of each operational period. After this initial longer period of time the heat supply unit may be turned ON for shorter periods of time or turned ON for one or more longer periods of time before being turned ON for shorter periods of time.

The controller receives activation signals and deactivation signals from external devices, optionally from the same external device. An activation signal may be provided by a conventional timer to turn the heat supply unit ON at a particular time or by a thermostat to turn the heat supply unit ON when a measured temperature (e.g. a building/room temperature) falls below a setpoint temperature. Similarly, the deactivation signal may be provided by a conventional timer to turn the heat supply unit OFF at a particular time or by a thermostat to turn the heat supply unit OFF when a measured temperature rises above a setpoint temperature. Activation and deactivation signals may also be provided in response to unscheduled heating demands made by the user. These activation and deactivation signals would typically be used to turn the heat supply unit ON and OFF but during these cycles the activation periods are interrupted by the controller of the present invention which provides its own sequence of control signals to control the ON/OFF operation of the heat supply unit.

Each successive operational period of the controller will be started by an activation signal and ended by a deactivation signal.

The heat supply unit is preferably controlled in the same way during each operational period. However, different control programs (e.g. timings) can be applied during different operational periods.

At the start of each operational period the heat supply unit is preferably turned ON for an initial period of time. This raises the temperature of the water in the heating system—and hence raises the temperature of the parts of the heating system that are used to actually provide space heating (e.g. radiators)—to a desired (or ‘target’) temperature. Once the initial period of time has elapsed, the control circuit will periodically turn the heat supply unit OFF and ON until the end of the particular operational period. In other words, during each operational period there will normally be periods of time when the heat supply unit will not be supplying heat to the heating system even though heat is being demanded by the external device(s).

The periods of time during which the heat supply unit is turned OFF by the control circuit are not long enough for the temperature of the radiators to reduce significantly and the heating system will continue to provide space heating even when the heat supply unit is not supplying heat. A small fall in the radiator temperature (e.g. one or two ° C.) is expected when the heating supply unit is turned OFF but this does not have a significant affect on the space heating. This means that the timings are typically pre-programmed to achieve the target temperature of the heating system (i.e. the controller is temperature dependent) even though the heat supply unit is turned ON and OFF in response to control signals that are based entirely on an internal timer and are derived independently of temperature. Periodically turning the heat supply unit OFF and ON during each operational period results in energy savings without compromising heat output.

In a typical control program, at the start of each operational period the heat supply unit will be turned ON for an initial period of 15 minutes to raise the temperature of the heating system to its normal operating temperature. The heat supply unit will then be turned OFF for 5 minutes, ON for 10 minutes, OFF for 5 minutes, ON for 10 minutes etc. until a deactivation signal is received and the particular operational period ends.

In another control program, at the start of each operational period the heat supply unit will be turned ON for an initial period of 15 minutes to raise the temperature of the heating system to its normal operating temperature. The heat supply unit will then be turned OFF for 5 minutes, ON for a further period of 15 minutes to further raise the temperature of the heating system, OFF for 5 minutes, ON for 10 minutes, OFF for 5minutes, ON for 10 minutes etc. until a deactivation signal is received and the particular operational period ends.

The various timings will normally be pre-programmed but in some circumstances a user may be able to select from different pre-programmed options.

As soon as a demand for heat is received by the controller (i.e. an activation signal is received) then the heat supply unit is turned ON to start and raise the heating system to the desired (or ‘target’) temperature to maintain user comfort.

The present invention further provides a method of controlling a heat supply unit for supplying heat to a heating system during successive operational periods of a controller, each operational period being started by an activation signal provided to the controller from an external device and being ended by a deactivation signal provided to the controller from an external device, the method comprising the steps of providing a sequence of control signals to periodically turn the heat supply unit ON and OFF, wherein at least one period of time for which the heat supply unit is turned ON is longer than at least one other period of time for which the heat supply unit is turned ON during a particular operational period.

The present invention further provides a time-based controller that optimises the extraction of latent heat from a heating system, after a heat supply unit is turned OFF, whilst keeping the temperature of the heating system to within about 10% of a target temperature.

DRAWINGS

FIG. 1 is a schematic drawing showing a heating system incorporating an electronic controller according to the present invention;

FIG. 2A shows a first example of a control program for controlling the operation of the heating system; and

FIG. 2B shows a second example of a control program for controlling the operation of the heating system.

With reference to FIG. 1, a domestic heating system includes a gas boiler 2 that supplies hot water to radiators (not shown). An electronic controller 4 includes a control circuit that provides ON and OFF signals to the boiler controller 6 that is integrated with the boiler 2 and controls the direct operation of the gas burners etc. Although in FIG. 1 the electronic controller is shown as a separate or stand-alone component, in practice it can be physically integrated with the boiler controller 6. When the electronic controller 4 sends an ON signal the boiler controller 6 turns to boiler ON so that it starts supplying hot water to the radiators (not shown) for space heating and when the electronic controller sends an OFF signal the boiler controller turns the boiler OFF.

The electronic controller 4 receives activation (ACT) signals and deactivation (DEACT) signals from one or more external devices. FIG. 1 shows two typical external devices, namely a timer 8 which provides activation and deactivation signals at certain user-defined times of the day and a thermostat 10 which provides activation and deactivation signals depending on whether a measured temperature is above or below user-defined setpoint temperatures. Other external devices can be used.

As shown in FIGS. 2A and 2B, each operational period of the electronic controller 4 is started by an activation (ACT) signal and ended by a deactivation (DEACT) signal. The activation and deactivation signals can be provided by any of the external devices. Each operational period essentially represents a period of time (T_(op)) when space heating is demanded. Within each operational period the electronic controller 4 operates a pre-programmed control program which sends a sequence of ON and OFF signals to the boiler controller 6 so that the boiler 2 is turned ON and OFF.

The electronic controller 4 is optionally provided with several pre-programmed control programs which can be selected by a user.

As soon as the electronic controller 4 receives an activation (ACT) signal from an external device the electronic controller sends an ON signal to the boiler controller 6 so that the boiler 2 is turned ON and starts to provide hot water to the radiators (not shown) for space heating. The boiler 2 is turned ON for an initial period of time (T_(i)) and is then subsequently periodically turned OFF and ON by the boiler controller 6 under the control of the electronic controller 4 as shown in FIG. 2. The initial period of time (T_(i)) is longer than the other periods of time (T_(on)) when the boiler 2 is turned ON so that the radiators (not shown) are raised to the desired (or ‘target’) temperature to maintain user comfort at the start of each operational period.

The boiler 2 continues to be periodically turned OFF and ON by the boiler controller 6 under the control of the electronic controller 4 until the electronic controller receives a deactivation (DEACT) signal from an external device.

In the typical example shown in FIG. 2A the first activation (ACT) signal is received from the timer 8 at a start time (e.g. 7.00 am). The first operational period will continue until the first deactivation (DEACT) signal is received from the thermostat 10 when a measured temperature rises above a setpoint temperature. The second operational period will start when the second activation (ACT) signal is received from the thermostat 10 when a measured temperature falls below a setpoint temperature and continues until the second deactivation (DEACT) signal is received from the thermostat when a measured temperature rises above a setpoint temperature. The third operational period will start when the third activation (ACT) signal is received from the thermostat 10 when a measured temperature falls below a setpoint temperature and continues until the third deactivation (DEACT) signal is received from the timer 8 at an end time (e.g. 9.30 am). The control program timings for each operational period are the same:

-   -   T_(i)=15 minutes     -   T_(off)=5 minutes     -   T_(on)=10 minutes

But it will be readily appreciated that other timings may be used depending on the heating system and its operational requirements. For example, the first time the boiler 2 is turned ON again after the initial period then it may be turned on for a longer period of time (T_(i)) and then each subsequent time the boiler is turned ON it may be turned on for a shorter period of time (T_(on)). Such an alternative control program shown in FIG. 2B would provide two longer periods of time at the start of each operational period to help raise the temperature of the heating system to its target temperature. 

1. A time-based controller specifically adapted for a heat supply unit for supplying heat to a heating system, the heating system including a part that provides space heating, the controller including a control circuit that is adapted to provide a sequence of control signals to periodically turn the heat supply ON and OFF during successive operational periods of the controller, each successive operational period being started by an activation signal provided to the controller from any of one or more external devices and being ended by a deactivation signal provided to the controller from any of the one or more external devices, wherein during a particular one of the successive operational periods the control circuit is adapted to provide at least one period of time for which the heat supply unit is turned ON that is longer than at least one other period of time for which the heat supply unit is turned ON, and wherein the periods of time during which the heat supply unit is turned ON and OFF by the control circuit during each successive operational period are pre-programmed.
 2. The time-based controller of claim 1, wherein the control circuit is adapted to provide a control signal to turn the heat supply unit ON for an initial period of time at the start of each successive operational period, the initial period of time for which the heat supply unit is turned ON being longer than at least one other period of time for which the heat supply unit is turned ON during a-the particular one of the successive operational periods.
 3. (canceled)
 4. (canceled)
 5. The time-based controller of claim 1, wherein during each successive operational period, the control circuit is adapted to provide at least one period of time for which the heat supply unit is turned ON that is longer than at least one other period of time for which the heat supply unit is turned ON. 